The present invention relates to a method for delivering coffee beverages from capsules designed to be extracted under pressure and containing a substance for the preparation of a coffee beverage.
Coffee cups can be produced from filter coffee machines. However, as a result of a “light” extraction of the coffee, the resulting extract usually has low coffee solids concentration, a low aroma profile, and little or no “crema” on the top.
Capsules designed to be extracted under pressure and containing a substance for the preparation of a beverage exist on the market. They provide a better extraction of coffee, i.e., a higher “extraction yield”, more aroma and a better “crema”, more convenience in operation and they ensure freshness of the substance contained therein. As a result, the delivery of freshly extracted beverages of constant quality is better ensured.
For instance, the actual system commercialized under the trademark “Nespresso®” is appreciated for producing good quality short cups of coffee and long cups of coffee. A short cup of coffee is defined as containing less than 50 grams of coffee liquid extract in the cup and more specifically about 40 g for the espresso type and about 25 g for the Ristretto type. Due to the high pressure extraction conditions maintained in the capsule, in the order of 10-20 bar, the liquid extract which is delivered can be given desirable quality attributes in terms of coffee yield, coffee solids and “crema” and within a delivery flow time which is found acceptable for the user. Some consumers however, prefer to have the option to also prepare a long cup of coffee with the existing capsules. A long cup of coffee is defined as containing about 110 (+/−10) grams of coffee liquid extract in the cup. In order to deliver a longer cup of coffee, a higher amount of water needs to be sent through the capsule. Therefore, typically a “long coffee” takes a too long time to be delivered, i.e., one minute or more, and the resulting beverage can taste too bitter and harsh and might be slightly thin or watery. The delivery time, which exceeds one minute, is also unacceptable on a commercial standpoint and inconvenient to the consumer who wants to prepare several cups in a row.
EP 1 566 127 A2 has proposed a solution for a system adapted to deliver a short or long coffee using the same coffee extraction device and the same capsule format. The long coffee capsules have a retaining membrane of puncture resistance of from 0.6 to 1.1 mJ and a coffee granulometry of from 300 to 600 microns.
The present invention aims at a significant improvement to the capsule system of the prior art. In particular, a main objective is to reduce flow time of the coffee capsules to deliver a long coffee extract while at the same time maintaining or even improving the quality attributes of the coffee, in particular, a desirable strength (e.g. expressed by its “extraction yield”) and also a sufficient thickness and texture of crema.